Related Experiment Video
Updated: Jun 6, 2025
Physiology Lab Demonstration: Glomerular Filtration Rate in a Rat
Published on: July 26, 2015
Determination of urine volume and glomerular filtration rate using d-serine and d-asparagine
Ryo Tanaka1, Shinsuke Sakai2, Ayumu Taniguchi3
1Department of Urology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Background:
Measurement of glomerular filtration rate (GFR) is subject to inaccurate urine collection. Clearances of d-serine and d-asparagine, rare enantiomers of amino acids, are the measures of GFR since they are almost free of tubular secretion and reabsorption. We hypothesize that d-serine and d-asparagine can accurately determine urine volume and GFR.
Methods:
This cross-sectional observational study included 209 living kidney transplant donors and recipients for whom GFR was measured using the clearance of inulin. Assuming that urine excretions of d-serine and d-asparagine are constant and using urine levels of d-serine and d-asparagine from each urine collection, an equation for estimated urine volume (eUV) was established. Based on the eUV, the abnormal urine volume was replaced with an estimate with which the GFR was re-evaluated.
Result:
Clearances of d-serine and d-asparagine were minor in proportional biases when compared with that of creatinine. Using 627 urine collections, the equation for eUV (mL/min) was established as 21.88/urine d-Ser(0.40 + 0.20 × log10(urine d-Asn)). Using eUV, we identified 20 instances where urine collection volumes varied significantly from the estimated values. After replacement with eUV, measured GFR (mGFR) was corrected to adjusted mGFR, which was within approximately 20 mL/min/1.73 m2 of the mGFR.
Conclusion:
d-Serine and d-asparagine are nearly completely excreted in urine after glomerular filtration, enabling the estimation of urine volume and correct mGFR. Besides reflecting GFR, d-serine and d-asparagine can be used to estimate urine volume. By applying the eUV method, mGFR determined using clearance methods becomes more accurate.
Related Concept Videos
01:02Renal Drug Excretion: Glomerular Filtration
Drugs gain access to the kidney via the renal artery, which progressively branches off into afferent arterioles....
01:28Glomerular Filtration Rate and its Regulation
GFR regulation involves two primary intrinsic controls: the myogenic and tubuloglomerular feedback mechanisms.
The myogenic...
01:23Renal Clearance
Renal clearance refers to the volume of plasma cleared of a specific substance, such as creatinine, per unit of time. To measure clearance, urine samples are collected over a 24-hour period during each bladder voiding, followed by a single blood sample at the...
01:07Determination of Renal Drug Clearance: Graphical and Midpoint Methods
The graphical method involves plotting the rate of drug excretion in urine against the plasma drug concentration. By analyzing the graph, the clearance can be calculated and obtained. Drugs rapidly excreted by the kidneys exhibit a...
01:17Factors Affecting Renal Clearance: Renal Impairment
One condition associated with renal failure is uremia. Uremia is characterized by impaired glomerular filtration and fluid accumulation in the body. This condition hinders the renal clearance of drugs, resulting in drug accumulation and potential...